Drywall panel carrier attachable to lift platform

FIELD OF THE INVENTION

This invention relates to handling of building panels at construction sites and more particularly to equipment for transporting and lifting of panels to an elevated position convenient to installers.

BACKGROUND OF THE INVENTION

Handling of building panels such as drywall or “Sheetrock” panels has presented difficulties, especially for large panels being installed in commercial buildings at heights above a first floor level. Drywall panels for such applications may be as large as four feet by twelve feet and weigh one hundred pounds or more. It is readily apparent that any improvements in equipment and procedures for lifting such panels to a required elevated location would be welcomed by installers.

Use of scissors-type lift machines has become a common practice at commercial building sites. These devices have sets of paired extendable arms mounted on a wheeled and powered chassis and a work platform supported by the arms. For safety reasons the platforms include horizontal rails around their outer edges supported by upright posts. The rail structure generally includes an upper rail some three feet above the platform floor and a lower rail halfway between the floor and upper rail. The rails generally take the form of square metal tubing. Lift platforms may be eight feet by three feet and provide space for two to three workmen. Machines of this type are exemplified by U.S. Pat. No. 6,158,550, issued Dec. 12, 2000 to Arnoldy, which patent is hereby expressly incorporated by reference.

Attempts have been made to use existing lift devices for lifting large panels along with the workmen to an elevated working level, but various disadvantages are presented. If the panel is longer than the platform it could only be carried on top of or outside of the rails, which would be difficult or even unsafe to the workers. Also the panel might end up in a position requiring awkward moves by the workman to place the panel in final location. In addition, operations such as sliding a panel over a platform or rail might result in damage to the panel.

SUMMARY OF THE INVENTION

The present invention is directed to apparatus for lifting and transporting panels of material such as drywall to a desired location at a construction site. The apparatus comprises a pair of panel-receiving legs attachable to horizontal side rails of a lift platform, with the legs when attached extending generally in a vertical direction. Square metal tubing is a suitable material for making the legs.

Each of the legs has a top, bottom and midpoint along its length, an inside surface facing the platform from the outside when installed and an outside surface facing the opposite direction. Clamps for making connection to upper and lower rails of a lift platform may be removably attached to the rail on the inside of the legs, an upper clamp at the top of the leg and a lower clamp at a midpoint. The legs have a panel-receiving channel provided at the bottom of the leg and on the outside thereof. A low friction contact member at base of the channel is used to obtain enhanced rolling or sliding movement of panels, and a horizontal guide serves to return the panels in position.

Low friction contact surfaces may also be provided at various other locations so as to keep the panels from being slid over the surfaces which present higher friction. This feature may be implemented in the form of rollers located at the base of the channel at the top of the leg, at a side or the channel above the base roller and at a midpoint of the leg. In each case the roller is placed so that its circumference extends to provide space away from surfaces of other structural members.

To provide for easier handling of panels and to keep them from falling out of the channel, the leg may be adapted for being inclined outward at the bottom at an acute angle such as ten to fifteen degrees from the vertical. This result may be obtained by mounting the lower clamp on a standoff member at a suitable length whereby the bottom of the leg is projected outward.

Variations in the distance between upper and lower rails of different platform lifts may be accommodated by pivotally mounting the lower clamp support on the leg and by providing a series of vertically separated holes through the leg to allow for adjustment by insertion of a pin in a selected mounting hole. Use of the apparatus for narrower panels having a width such as two foot may be enabled by placement of the channel structure at a midpoint of the legs. For this purpose this component may be removably mounted for attachment at the midpoint as well as at the bottom of the leg.

Another desirable feature of the invention is to provide a braking mechanism for the roller at the base of the channel to prevent unintended rolling or sliding when the platform is moved. Locking of the load-bearing wheel at the base of the channel, as by insertion of a pin, may be employed.

Apparatus embodying the invention provides important advantages, particularly in the ease and convenience of moving large and heavy panels to a position which is optimum for further movement into the final location for installation. Safety and productivity of panel installers are thereby enhanced, and damage to panels is reduced.

It is accordingly an object of this invention to provide a panel-carrying attachment for lift platforms.

Another object is to provide a panel-carrying attachment having low friction, load-bearing surfaces enabling ease of loading.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a panel-supporting leg embodying the invention.

FIG. 2 is an elevational view thereof taken from a side.

FIG. 3 is an elevational view taken from the outside of the leg when installed.

FIG. 4 is a perspective view of a panel-receiving assembly removably attachable for use with narrow panels.

FIG. 5 is a perspective view showing a pair of legs installed on rails of a lift platform.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 of the drawings there is shown a panel-supporting leg <b>10</b> which is a component of a panel-lifting and carrying apparatus embodying the invention. Two such legs are required at spaced-apart locations along the length of a lift platform for effective support of panels. Each of the legs has a pair of clamps located on the inside of the leg, upper clamp <b>12</b> attachable to an upper horizontal rail <b>14</b> of a lift platform <b>16</b> and a lower clamp <b>18</b> attachable to a lower rail <b>20</b> of the platform.

Leg <b>10</b> preferably takes the form of a straight piece of square metal tube which may have a width of one inch and a length of three feet. The leg has a top end <b>22</b>, a bottom end <b>24</b> and a middle area <b>26</b> between the ends. Flat side <b>28</b> of the leg is positioned on the inside of the tube facing the rail and opposing flat side <b>30</b> faces outward away from the rail.

Upper jaw clamp <b>12</b> is rigidly connected to plate <b>32</b>, which in turn is joined to top end <b>22</b> of the leg and which extends inward to flat side <b>28</b> of the leg. Upper jaw <b>34</b> of this clamp comprises a segment of L-shaped angle iron adapted to fit over the inside upper corner of rail <b>14</b>. Lower jaw <b>36</b> of this clamp has a similar structure to the upper jaw and is supported by adjustable screw <b>38</b> mounted on stud <b>39</b> connected to the leg.

Lower clamp <b>18</b> is also located on the inside of the leg and is arranged to come into clamping contact with lower rail <b>20</b>. Clamp <b>18</b> has an upper jaw <b>42</b> and lowern jaw <b>43</b> supported by an adjustable screw <b>45</b> mounted on support arm <b>49</b> which is connected to standoff arm <b>40</b>. This clamp in the embodiment shown is connected to the leg at a middle portion <b>26</b>, and may be varied to compensate for differences in rail placement on different platforms, as is described below. A standoff arm <b>40</b>, disposed between upper jaw <b>42</b> of clamp <b>18</b> and attachment bracket <b>44</b> causes the bottom end of the leg to be projected outward away from the platform at a selected acute angle sssuch as 10 to 15 degrees from vertical. This extent of slanting enables easier grasping and handling of the panel, particularly when the panel is removed by being lifted in a direction backward over the workmens' heads. Capability for movement of clamp <b>18</b> over a narrow range is provided by pivotally mounting of bracket <b>44</b> around pin <b>46</b> through hole <b>50</b>. A series of vertically spaced apart alternate holes <b>50</b><i>a </i>to <b>50</b><i>d </i>are provided to allow for mounting at varying heights.

A panel-receiving channel <b>23</b> (FIG. 2) is provided at the bottom end <b>24</b> of the leg and adjacent to outside flat side <b>30</b>. The channel may be formed by an end portion <b>51</b> of the leg, a horizontally extending bottom plate <b>52</b> and a short vertically extending plate member <b>54</b>, which may be a bent over extension of plate <b>52</b>. A horizontally extending guide <b>55</b> in the form of a plate attached to vertical plate <b>54</b> and having end portions <b>56</b> bent outward is provided to restrain panels from moving laterally out of position. A roller <b>58</b> is mounted on axle <b>59</b> extending from leg portion <b>51</b> to vertical plate <b>54</b>, providing an axis of rotation perpendicular to the leg. The weight of the panel being carried rests fully on the load-bearing roller <b>58</b> so that a very low extent of friction is encountered when the panel is slid into position.

In addition to roller <b>58</b> located at the base of the channel other rollers may be provided at the top end of the leg and at side positions to facilitate handling of panels and to restrain panels from coming into contact with other structural elements. Roller <b>60</b> is placed at the top end <b>22</b> of the leg, mounted on U-shaped bracket <b>62</b> on axle <b>64</b> which is generally perpendicular to the leg. This roller facilitates removal of the panel when being raised upward for unloading. Placement of the roller with its circumference slightly outside of side <b>30</b> of the leg keeps the panel from coming into contact with the leg. Sets of rollers <b>66</b>, <b>68</b> and <b>70</b>, <b>72</b> are provided on opposing sides of the middle <b>26</b> and bottom <b>24</b> of the leg, respectively. These rollers are mounted on axles <b>74</b>, <b>76</b> and <b>78</b>, <b>80</b> parallel to the leg and supported by plates <b>82</b>, <b>84</b> and <b>86</b>, <b>88</b> (FIG. 3) perpendicular to the leg. Placement of these rollers with their circumference spaced outside of the level of leg avoids contact of panels with the legs and facilitates movement of panels into and out of position.

It is noted that only one of the rollers of sets <b>66</b>, <b>68</b> and <b>70</b>, <b>72</b> would be required in operation, that one being the roller which first comes into contact with a panel being loaded, that is the roller on the side facing the panel in the direction from which the panel is moving. Placement of rollers on both sides is preferred, however, to enable any leg to receive panels from both directions.

Ball-bearing rollers with wheels made of heavy plastic such as are used in roller skates may be used, with suitable dimensions being a diameter of two inches and a width of one and one-fourth inches.

FIG. 1 shows a safety feature in the form of a roller-locking mechanism incorporated in apparatus of this invention. To prevent panels from sliding off of the channels in which they are supported, particularly when the lift platform is being moved after loading, a locking pin <b>61</b> may be inserted into a hole <b>53</b><i>a</i>-<b>53</b><i>d </i>in the bottom roller <b>58</b>, the pin also passing through a hole in plate <b>54</b>. To avoid loss of pin <b>61</b> it may be secured to the plate by means such as a chain <b>57</b>.

FIG. 4 shows an embodiment wherein a channel assembly <b>90</b> is provided for removable attachment to leg <b>10</b> at an intermediate position adjacent to rollers <b>66</b>,<b>68</b>, The assembly is formed into a U-shaped bracket <b>91</b>, including a vertical segment <b>89</b> attachable to leg <b>10</b> at holes <b>92</b>, <b>93</b>, a base segment <b>94</b> and an outer vertical segment <b>95</b> connected to guide <b>96</b> at the upper end thereof Roller <b>97</b> mounted on axle <b>98</b> is positioned in the same manner as for roller <b>58</b>. Connection of the assembly to leg <b>10</b> is enabled by bolt <b>99</b>, which extends through hole <b>92</b>. Axle <b>98</b> which supports yhe roller may also extend slightly into hole <b>93</b>. This removable assembly could also be used at the bottom of the leg by making slight modifications to the leg. This assembly provides for convenient handling of narrow panels having a width such asa two feet, which might otherwise come into direct contact with surfaces of the legs.

In order to prevent overloading of the panel lifting apparatus, as might occur if too many heavy panels were placed on the legs at one time, the width of panel-receiving channels <b>23</b> is preferably limited to a distance between rollers <b>70</b>, <b>72</b> and guides <b>55</b> of about one to one and one-half inch. This would allow room for only one panel, with enough slack provide to enable free movement. Also, after one panel is loaded on the supporting legs, it would be difficult to load a second one because rotation of the rollers when the second panel is being slid into position would cause the first panel to be moved outward.

In operation of the apparatus of this invention for installing wall panels, it is preferred to bring the lift platform, when loaded, into a position such that the legs and supported panel are located on a side rail away from the wall. This allows the opposite side of the platform to be brought closer to the wall and minimizes the distance over which the installers would need to reach. Removal of the panel from the legs and into position on the wall also proceeds more smoothly than if the legs were on a side adjacent the wall.

Although the invention is described with reference to drywall panels, it is to be understood that the panels may be comprised of other materials such as plywood and other wood-based compositions as well as polmeric materials such as poly-carbonates and glass.

The posts used for panel-supporting legs preferably may be metal tubes having a rectangular or square cross section but the invention includes posts in the form of shapes such as angle iron, beams, or the like.

It is to be understood that although the invention is described above in terms of specific embodiments, it is not so limited, but is limited only as defined in the approved claims.